agrams said:

khk, did you measure it, or use the 5 cut method? I found the 5 cut method is pretty simple.

also, it is hard to see, but before you put the vertical piece on the back (side towards you that you reference the wood on when you push), cut a small chamfer on the lower corner, that way you have a small relief sawdust can collect in and not push your piece off the reference board. You will still need to blow it out some, but a little dust won't throw off your piece like a square corner.
I used the 5 cut method. I watched two main you tube videos on making the whole thing and when I went to reference one for which way my adjustment should go after the first test cut, the one I chose said the wrong thing. So my difference became even worse and caused me a lot of wasted extra time. I think I finally got it on the 5th try after watching the other video and having them explain moving it the correct way.

I used a 1/8" roundover on the bottom of the push piece, but it probably isn't enough to help properly. I just don't feel like taking it apart and trying to line it up again with all the holes in the bottom already.

I planned to put a safety block on exit side of the push piece, but I just haven't gotten there yet.